JP2003224515A - Method for simulating operating condition of telecommunication system and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for simulating operating conditions of a telecommunication system which replace the conventional Monte Carlo method. <P>SOLUTION: The invention relates to the method for simulating operating conditions of the telecommunication system including radio base stations (BS1, BS2, BS3) and mobile users (UE11, UE21, UE31), forming together a communication network, essentially consisting in making a plurality of snapshots of the system, each snapshot being descriptive of a determined configuration of the communication network, wherein two successive snapshots are linked together by at least one correlating parameter (V11, V21, V31). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to at least two radio base stations and 2 forming together a communication network.
A method for simulating operating conditions of a telecommunication system including one mobile user.

[0002]

2. Description of the Related Art Such methods are currently used to define a system capable of providing optimal communication services at a minimum cost, prior to the actual physical implementation of a telecommunications system. It is used to optimize the placement of radio base stations included in the system and the design of the decision making network infrastructure aimed at managing the network.

Known as mapping methods, several simulation methods currently used to optimize GSM-type telecommunications systems (also known as 2G (2nd Generation) systems) each involve a single method. Create a map showing a plurality of geographical coverage areas forming cells associated with the base stations of the. This map shall evaluate the coverage of the system according to the principle that if the mobile user is located in a cell and the associated base stations are not saturated, the mobile user will be provided with sufficient communication services. To enable.

UMTS type telecommunications system (3G (3rd
Quality of service (also known as generation) systems) cannot be obtained accurately with the method described above.
This is mainly a frequency that allocates two different communication frequencies to two different mobile users located in the same geographical area, such as is done in 2G systems, to minimize interference between them. This is because the 3G system does not plan. In 3G systems, such frequency planning is not performed, so that communication interference between mobile users can and will occur, adversely affecting the quality of each ongoing communication. The extent of this adverse effect varies from user to user depending on the particular circumstances of each user,
It cannot be predicted by the above method.

Another known method (usually called the Monte Carlo method) consists mainly in creating a plurality of snapshots, each representing a predetermined randomly generated system situation. Each snapshot then shows the location of all mobile users of the system in the corresponding situation, the base station with which the user is communicating, and the power level each mobile user applies to his ongoing communication, This is the theory of the amount of interference generated by the above-mentioned user with respect to other users located in the vicinity thereof, and thus the degree to which the interference generated by the other user in each situation randomly generated adversely affects each user. It is possible to estimate it.

The Monte Carlo method therefore makes it possible to establish, for each randomly generated situation, the number of mobile users who are provided with sufficient communication services,
It enables a statistical evaluation of the overall communication quality provided by the simulated system.

However, the effectiveness of the Monte Carlo method is impaired by the following problems.

Since this method performs a statistical analysis of the simulated system, it requires a large number of snapshots to make such analysis reliable. Therefore, in order to analyze a situation in which they are generated at random and often conflict with each other, it is necessary to use a huge amount of computer resources (computi
ng resources) are required. Thus, a set of such situations is analyzed as forming a whole and does not represent a realistic evolution in the operating state of the simulated system. This problem is even more important in simulations involving, for example, tens of thousands of users and hundreds of base stations, as the number of simulated users and the size of the system are important.

Further, the Monte Carlo method is simulated by considering, among other parameters, the interference generated by the user and the adverse effects of the interference on ongoing communication in each randomly generated situation. While allowing an overall assessment of the average communication quality offered by the 3G systems, it is not possible to monitor individual communications to assess the perceived quality of service offered to individual users. This quality of service is the ultimate metric because one of the main goals of system simulation is to help define a system that meets the needs of the user for customer satisfaction.

[0010]

SUMMARY OF THE INVENTION The present invention aims to solve the above problems by providing a method for simulating the operating conditions of a telecommunication system. This method requires more computational power than the Monte Carlo method.
It has low (computing power) and makes it possible to evaluate the quality of service provided to individual users of the system.

[0011]

To this end, according to a first aspect of the present invention, in a simulation method, which essentially consists in creating a plurality of snapshots of the system, , Each of which represents a predetermined configuration of the communication network, wherein at least one correlation parameter links two consecutive snapshots together.

Linking two consecutive snapshots to each other makes it possible to reduce the number of situations generated to one that is consistent with each other and thus realistic, which is in accordance with the invention. It makes it possible to reduce the amount of computational power required to carry out the simulation method, eg for Monte Carlo methods. This advantage of the present invention is important when simulating a large scale system containing, for example, hundreds of base stations and tens of thousands of mobile users.

According to a second aspect of the invention, the correlation parameter undergoes a predefined change over time.

Such a choice as to the correlation parameter makes it possible to obtain a historical indication of the operating state of the system and thus to track the evolution of individual communications over time, which leads to the individual It makes it possible to evaluate the quality of service provided to the user.

In a particular embodiment of the invention, the position of at least one mobile user and the velocity vector associated with that user are used as correlation parameters.

In a preferred embodiment of the invention, the amount of power of the signal transmitted by at least one mobile user is used as a correlation parameter.

In a variant of this advantageous embodiment of the invention, the data rate of at least one ongoing communication established between the mobile user and the base station is used as a correlation parameter.

These advantageous embodiments of the invention make it possible to consistently realistically model the interference generated by the user, which can adversely affect each ongoing communication. These embodiments also allow simulating the appearance or disappearance of communications in the vicinity of each user. This is a concept given only with respect to the history display provided by the present invention and may affect the quality of ongoing communication of the user.

The invention also relates to a simulation device intended to carry out a method as described above.

The characteristics of the invention mentioned above, as well as others, will emerge more clearly from a reading of the following description given in relation to the accompanying drawings, amongst which:

[0021]

1 shows diagrammatically a simulation device SD intended for simulating the operating conditions of a telecommunication system using the method according to the invention. This device SD comprises a first database GD intended to store geographical data (eg models of obstacles such as buildings, mountains etc.) relating to the terrain on which the telecommunication system is to be arranged. The simulation device SD further includes data regarding the wireless base stations forming the network included in the system (the geographical position of each base station, the maximum number of communications that each base station can process at a given moment, or each base station own station). Second, which is intended to store information such as maximum transmission power that can be applied to ongoing communication
Database BSD of. The simulation device SD also comprises a third database UED intended to store a set of files, said files being:
Each is associated with a mobile user that appears during the simulation and includes, in chronological order, consecutive coordinates, rates, transmit powers or data rates that are attributed to ongoing communications between each user and the base station. Thus, the first and second databases GD and BSD contain data of a structural nature which describes the arrangement of the wireless networks comprised in the system and the geographical constraints in which the networks operate, while the third database UED. Contains dynamic data representing events that occur during the operation of the system.

In this embodiment of the invention, the first,
Second and third databases GD, BSD and UE
D is intended to be loaded by the user of the simulation device SD via the loading interface LDINT.

The simulation device SD includes the first and
Second and third databases GD, BSD and UE
An arithmetic unit CU whose purpose is to process the data provided by D on respective data signals Dg, Dbs and Due
, Which is clocked by the clock signal Clk provided by the clock generator XTAL. In the analysis step starting at each active edge (eg rising edge) of the clock signal Clk, the computing unit CU
Retrieving a set of data from the first, second and third databases GD, BSD and UED, in particular which mobile user is communicating with which base station, the power each user applies to his ongoing communication. A snapshot of the system is created by synthesizing the data by determining the amount and / or amount of interference generated by each user and the negative impact that this may have on other users' communications. The third database UED can be configured to provide, among other correlation parameters, instantaneous values of specified data rates for various communications supported by the system at corresponding moments, in which case the computing unit CU. Determines the amount of power that must be applied to each mobile user's ongoing communication to ensure that the corresponding specified data rate is respected, and the interference level associated with this amount of power. In another possible embodiment, the third database UED provides the value of the power applied to each ongoing communication and the calculator C
U need only determine during each analysis step only the amount of interference generated by the ongoing communication.

At the end of each analysis step, the computing unit CU
A set of output data signals Dout representing the result of the above synthesis
Is sent to the register REG for storage. This register REG is linked to a display interface DISP intended to convey the result of the simulation to the user of the simulation device SD. The store operation performed by the register REG can be ordered by a clock signal obtained from the clock signal Clk (for example, a signal having a phase opposite to that of the clock signal Clk as in this embodiment), which means that the data is safe. Provides sufficient setup time to be stored in. The display interface DISP may be provided with a means for interpreting the output data Ds, which means that the display interface DISP has a value of a parameter (e.g., power-to-interference ratio) indicating the communication quality attributed to each mobile user. Can be extracted from the output data Ds and such values can be displayed on a map representing the telecommunication system, for example in different colors or intensities.

Therefore, according to the present invention, the history display of the operating state of the system to be simulated is displayed on the simulation device S.
To provide users of D, and thus to track the evolution of individual communications over time,
This makes it possible to evaluate the quality of service offered to individual users.

FIG. 2 shows in the same figure SNPS 12 two consecutive snapshots of a very simple telecommunication system made according to the invention. This system
First, second and third radio base stations BS1, BS2 and BS3 to which first, second and third coverage areas (also called cells) C1, C2 and C3 belong respectively
including. The data describing the above features are of a structural nature and are stored in the first and second databases described above. It should be noted that the maximum amount of power that a base station can apply to its ongoing communications may change over time, thus causing changes around its coverage area. However, such data, although of a dynamic nature, is preferably stored in the second database described above.

In the first snapshot, the first and second
And the third mobile user (see UE11, UE21 and UE31) has their respective coordinates (x11, y1
1), (x21, y21) and the first position specified by (x31, y31). These coordinates form the first set of correlation parameters, the second set of correlation parameters being formed by the velocity vectors V11, V21 and V31 assigned to the respective mobile users UE11, UE21 and UE31. The values of these correlation parameters can be retrieved from the third database mentioned above.

To simplify the drawing, in this example, 2
Considering only the dimensions, all mobile user movements are coplanar. A third correlation parameter, such as the power that each mobile user applies to his or her ongoing communication or a data rate specific to that communication, which cannot be shown in this figure, can also be used, to this effect Three
Stored in the database.

In the second snapshot, the first and second
And a third mobile user (UE12 in this case,
UE22 and UE32 refer to each coordinate (x
12, y12), (x22, y22) and (x32, y3
It is shown in the second position specified in 2). These coordinates may be supplied from the above-mentioned third database, but the above-mentioned coordinates (x11, y11), (x21, y2
1) and (x31, y31) in combination with the above-mentioned velocity vectors V11, V21 and V31, and may be calculated by a computing unit. New velocity vector V1
2, V22 and V32 are in this second snapshot respectively mobile user UE12, UE
22 and UE 32.

The fact that the first and second snapshots share a link makes it possible to see how the quality of ongoing communication is affected by the movement of the first, second and third mobile users. become. In the second snapshot, all three users are relatively close to each other,
On the other hand, it seems that they are far from their base stations. By moving away from the base station, each user applies a significant amount of power to his ongoing communications, causing significant interference. This interference makes other users very sensitive to their proximity. The history display provided by the invention makes it possible to observe the corresponding degradation in communication quality.
It should also be noted that the invention also makes it possible to simulate sudden interruption phenomena. This concept is, for example, in this example the coordinates (x
42, y42), and thus in the vicinity of other mobile users, such as the appearance of a fourth mobile user UE 42, which causes a deterioration in the communication quality perceived by each user, only makes sense by the above history display. Is.

Velocity vector V of the second snapshot
According to 12, V22 and V32, the third mobile user UE32 is able to access the third cell C3 to the second cell between this second snapshot and the next snapshot (not shown in this figure). Move to cell C2 and a handover occurs. Handover is a very frequent phenomenon in cellular telecommunication systems, and this simulation can only be done if the simulation method can express concepts such as previous cell and next cell. This is because according to this embodiment of the invention, two consecutive snapshots are linked by a correlation parameter whose value changes over time, which allows to define a time series in the course of the simulation. It is possible.

[Brief description of drawings]

FIG. 1 is a functional diagram showing a simulation apparatus using the method according to the present invention.

FIG. 2 is a schematic view showing two consecutive snapshots obtained by the simulation method according to the present invention in the same figure.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor François de Rick             France, 35700 Rennes, Avigne             De Buttes de Coesme 80 F-term (reference) 5K067 AA23 BB04 EE02 EE10

Claims (6)

[Claims] 1. A method of simulating an operating condition of a telecommunication system including at least two radio base stations and two mobile users forming together a communication network, the method making a plurality of snapshots of the system. In particular, each snapshot represents a predetermined configuration of the communication network, and a method of simulating an operating state of a telecommunication system in which two consecutive snapshots are linked together by at least one correlation parameter. 2. The method of claim 1, wherein the correlation parameter has a predefined change over time. 3. The method according to claim 2, wherein the position of at least one mobile user and a velocity vector associated with the user are used as correlation parameters. 4. The method according to claim 2, wherein the amount of power of a signal transmitted by at least one mobile user is used as a correlation parameter. 5. The method according to claim 2, wherein the data rate of at least one ongoing communication established between the mobile user and the base station is used as a correlation parameter. 6. An apparatus for simulating an operating state of a telecommunication system for carrying out the method according to claim 1.